XMonad.Layout.IndependentScreens

Utility functions for simulating independent sets of workspaces on each screen (like dwm's workspace model), using internal tags to distinguish workspaces associated with each screen.

Usage

You can use this module with the following in your ~/.xmonad/xmonad.hs:

import XMonad.Layout.IndependentScreens

You can define your workspaces by calling withScreens:

myConfig = def { workspaces = withScreens 2 ["web", "email", "irc"] }

This will create "physical" workspaces with distinct internal names for each (screen, virtual workspace) pair.

Then edit any keybindings that use the list of workspaces or refer to specific workspace names. In the default configuration, only the keybindings for changing workspace do this:

keyBindings conf = let m = modMask conf in fromList $
    {- lots of other keybindings -}
    [((m .|. modm, k), windows $ f i)
        | (i, k) <- zip (XMonad.workspaces conf) [xK_1 .. xK_9]
        , (f, m) <- [(W.greedyView, 0), (W.shift, shiftMask)]]

This should change to

keyBindings conf = let m = modMask conf in fromList $
    {- lots of other keybindings -}
    [((m .|. modm, k), windows $ onCurrentScreen f i)
        | (i, k) <- zip (workspaces' conf) [xK_1 .. xK_9]
        , (f, m) <- [(W.greedyView, 0), (W.shift, shiftMask)]]

In particular, the analogue of XMonad.workspaces is workspaces', and you can use onCurrentScreen to convert functions of virtual workspaces to functions of physical workspaces, which work by marshalling the virtual workspace name and the currently focused screen into a physical workspace name.

A complete example abusing many of the functions below is available in the XMonad.Config.Dmwit module.

type VirtualWorkspace = WorkspaceId

type PhysicalWorkspace = WorkspaceId

workspaces' :: XConfig l -> [VirtualWorkspace]

withScreens

Arguments

:: ScreenId

The number of screens to make workspaces for

-> [VirtualWorkspace]

The desired virtual workspace names

-> [PhysicalWorkspace]

A list of all internal physical workspace names

onCurrentScreen :: (VirtualWorkspace -> WindowSet -> a) -> PhysicalWorkspace -> WindowSet -> a

marshallPP :: ScreenId -> PP -> PP

This turns a naive pretty-printer into one that is aware of the independent screens. That is, you can write your pretty printer to behave the way you want on virtual workspaces; this function will convert that pretty-printer into one that first filters out physical workspaces on other screens, then converts all the physical workspaces on this screen to their virtual names.

For example, if you have handles hLeft and hRight for bars on the left and right screens, respectively, and pp is a pretty-printer function that takes a handle, you could write

logHook = let log screen handle = dynamicLogWithPP . marshallPP screen . pp $ handle
          in log 0 hLeft >> log 1 hRight

whenCurrentOn :: ScreenId -> PP -> PP

Take a pretty-printer and turn it into one that only runs when the current workspace is one associated with the given screen. The way this works is a bit hacky, so beware: the ppOutput field of the input will not be invoked if either of the following conditions is met:

1. The ppSort of the input returns an empty list (when not given one).
2. The ppOrder of the input returns the exact string "\0".

For example, you can use this to create a pipe which tracks the title of the window currently focused on a given screen (even if the screen is not current) by doing something like this:

ppFocus s = whenCurrentOn s def
    { ppOrder  = \(_:_:title:_) -> [title]
    , ppOutput = appendFile ("focus" ++ show s) . (++ "\n")
    }

Sequence a few of these pretty-printers to get a log hook that keeps each screen's title up-to-date.

countScreens :: (MonadIO m, Integral i) => m i

In case you don't know statically how many screens there will be, you can call this in main before starting xmonad. For example, part of my config reads

main = do
  nScreens <- countScreens
  xmonad $ def {
    ...
    workspaces = withScreens nScreens (workspaces def),
    ...
    }

Converting between virtual and physical workspaces

You shouldn't need to use the functions below very much. They are used internally. However, in some cases, they may be useful, and so are exported just in case. In general, the "marshall" functions convert the convenient form (like "web") you would like to use in your configuration file to the inconvenient form (like "2_web") that xmonad uses internally. Similarly, the "unmarshall" functions convert in the other direction.

marshall :: ScreenId -> VirtualWorkspace -> PhysicalWorkspace

unmarshall :: PhysicalWorkspace -> (ScreenId, VirtualWorkspace)

unmarshallS :: PhysicalWorkspace -> ScreenId

unmarshallW :: PhysicalWorkspace -> VirtualWorkspace

marshallWindowSpace :: ScreenId -> WindowSpace -> WindowSpace

Convert the tag of the WindowSpace from a VirtualWorkspace to a PhysicalWorkspace.

unmarshallWindowSpace :: WindowSpace -> WindowSpace

Convert the tag of the WindowSpace from a PhysicalWorkspace to a VirtualWorkspace.

marshallSort :: ScreenId -> ([WindowSpace] -> [WindowSpace]) -> [WindowSpace] -> [WindowSpace]

If vSort is a function that sorts WindowSpaces with virtual names, then marshallSort s vSort is a function which sorts WindowSpaces with physical names in an analogous way -- but keeps only the spaces on screen s.